https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97330
--- Comment #2 from David Binderman <dcb314 at hotmail dot com> --- Flags -Werror=implicit-int and -Werror=old-style-definition seem useful. Here is another reduced test case: int a, b, d; char c, e; void f(void) { char g = c; if (b) goto h; while (d) { e = c; h: d -= a; } }